Granule Strength Research Articles

IMPROVEMENT OF THE PRODUCT COMPOSITION FROM NITRIC ACID PROCESSING OF KYZYLKUM CARBONATE PHOSPHORITES

The process of producing NP-fertilizers by nitric-sulfuric acid decomposition of phosphate rock (17.20% P2O5) under thickening slurry conditions has been studied. It was shown that the higher the recycle ratio, the lower the moisture content of the final product. Increasing the HNO3 dosage above 30% and H2SO4 above 70% is undesirable, as the product's moisture content exceeds 6.03% and it has increased acidity. To avoid issues during ammoniation, an optimal rate of nitric and sulfuric acid was proposed—73.5-91%, which produced products containing 9.34-10.61% -P2O5total; 3.04-4.54% N; P2O5 digestive:P2O5 total = 73.4-82.3%; pH = 3.3-3.6, and granule strength of 2.1-2.3 MPa. The process of producing NPK-fertilizers was also studied by adding nitrogen components such as K2SO4, KCl, and K2CO3 to the products of complete nitric acid decomposition of washed and dried concentrate (24.10% P2O5) and fine fractions (18.55% P2O5). The process includes decarbonization and decomposition of the phosphate raw material (simultaneously in one apparatus), neutralization to a pH not lower than 3.5, evaporation of the slurry to a density of at least 1750 kg/m3, the addition of potassium salts at N:P2O5:K2O ratios of 1:1:1, 1.5:1:1, and 1:1.5:1, product granulation, drying in the presence of recycle, and cooling.

Characterization and evaluation of okra gum as a tablet binder

The type and amount of binders decisively influence the characteristics of tablets prepared by wet granulation procedure. Commonly used binders like acacia, gelatin, starch and hydrolyzed starch have natural origin. The aim of this study was to evaluate the effectiveness of a new binder extracted from Hibiscus esculentus (Okra gum) in tableting. Okra gum was extracted from the pods of Okra fruit by maceration in distilled water followed by filtration of viscous solution as well as precipitation of gum extract by using acetone. To evaluate the binder effectiveness, two models, including a placebo formulation (lactose) and a drug formulation (Acetaminophen, Ibuprofen, and/or Calcium acetate) were evaluated. Granules were prepared by different concentrations (0.5-6 %w/w) of Okra gum and tableted using a Kilian single punch press. Cornstarch (12.5 % w/w) and P.V.P (22 %w/w) were employed as the standard binders for comparison. The physical properties of the granulates and those of the tablets including disintegration time and dissolution rate were studied. The properties of granulates (bulk and tapped density, granule strength, flowability) as well as those of tablets (hardness, friability, disintegration time) were generally good. Moreover, the physical properties of Ibuprofen and Calcium acetate tablets containing Okra gum showed sufficient hardness, desirable disintegration time and low friability. The percent of drug released after 45 minutes were 15 %, 44 % and 96 % for Acetaminophen, Ibuprofen and Calcium acetate tablets, respectively. Okra gum produces some tablet formulations with good hardness and friability. However, this binder prolongs the dissolution rate of some slightly soluble drugs and hence may be good candidate for sustained release formulations. (Symecko C., Rhodes C, et.al.,1995)

Electrical conductivity of potassium polyferrite doped with doubly charged cations

To clarify the charge compensation mechanism and the way of alloying additives placement, the authors synthesised samples of potassium βʺ-polyferrites with a wide range of mole fraction of introduced doubly charged cations. For these samples, the authors measured the electronic conductivity, cationic conductivity, and performed X-ray diffraction (XRD) analysis. The authors identified the charge compensation mechanism in potassium β″-polyferrite when doped with divalent ions of calcium, strontium, magnesium, and zinc. The charge compensation mechanisms differ depending on the radius of the introduced doubly charged ion. The results of cationic conductivity measurements of potassium β″-polyferrites show the mobility reduction of large calcium and strontium cations of potassium ions. Such additives are quite promising for improving the mechanical strength and thermal stability of the catalyst granules. They also increase the chemical stability of the contact granules. Corrosion resistance of pellets is a critical parameter. It determines the period of effective functioning of the catalyst. The data on electronic conductivity allow one to conclude that the introduction of Mg2+, Zn2+ cations sharply reduces the electron exchange in the structure of potassium β″-polyferrite. This should inevitably cause deactivation of the catalyst, while Ca2+ and Sr2+ ions do not reduce the electron transfer rate. Moreover, using the proposed approach will intensify the research process.

Moisture content‐dependent mechanical behaviors of rice by experiments and composite models in finite element simulation

AbstractTo reduce the crushing rate and improve the yield of rice during the milling process, it is significant from a fundamental standpoint to understand the mechanical behaviors of rice under external loads. In this paper, the mechanical properties and fracture morphologies of rice with various moisture contents have been analyzed in detail by experiments and the finite‐element (FE) method. In FE simulations, two‐dimensional (2D) and three‐dimensional (3D) composite models have been established with the cohesive zone model characterizing the interface strength. The results show that the moisture content determines the endosperm cell wall interface strength, and a linear relationship between the interface strength and moisture content has been obtained. In particular, three fracture patterns of brown rice are observed by the competition between the interface strength of starch granule and endosperm cell wall interface strength. Good agreements between FE predictions and experimental results indicate that the combination of the 2D and 3D composite models with the cohesive zone model can provide accurate predictions of the fracture behaviors of brown rice. This investigation should be of great help for understanding the moisture content‐dependent compression and impact behaviors of rice.Practical applicationsBrown rice can be obtained by removing the husk through a hulling machine. During these processes, external loads, such as compression and impact, will damage the microstructure of brown rice, which results in a loss rate as high as 25%. Understanding the mechanical properties of brown rice with different moisture contents will be of great help in designing the equipment used in rice processing operations and extending the yield of polished rice.

PROCESSING OF A WASHED DRY CONCENTRATE CONTAINING 26% P2O5 INTO AMMOPHOSPHATE, SULPHO- AND NITROAMMOPHOSPHATE FERTILIZERS

The process of obtaining ammophosphate by means of phosphoric acid decomposition of washed dried concentrate (WDC) with 26 % Р2О5 and 10 % СО) - raw material for the production of thermally fired concentrate, has been studied. The extraction phosphoric acid contains (mass. %): 16.46 P2O5, 0.06 CaO, 1.11 MgO, 0.27 Fe2O3, 0.41 Al2O3, 2.98 SO3 and 0.99 F. The mass ratio of WPPA: WDC ranged from 100: 10 to 100: 30. Then acidic phosphate pulps (at 65°C) after 45 minutes were ammoniated to pH = 3.8, granulated and dried at 85 - 90°C. It has been shown that the nitrogen content in the finished product ranges from 4.92 - 7.11 %, total phosphorus (P2O 5t.) 41.48 - 46.44 %, phosphorus assimilated by plants (P2O5acceptable) 34.79 - 45.11 %, water-soluble phosphorus (P2O 5w.s.) 23.49 - 37.73 %. The addition of 5 - 7.5 % H2SO4 or HNO3 in the form of a monohydrate makes it possible to intensify the process of phosphoric acid decomposition of phosphate raw materials and to obtain sulfo- and nitroammophosphate with significantly highcontents of P2O5 acceptable and P2O5 w.s.. So, with a weight fraction of WDC equals to 30 and weight fractions of H2SO4 - 5 and 7.5, there have been 37.6 and 34.47 % P2O5 total in sulfoammophosphate; 24.11 and 22.06 % CaO t. , 88.75 and 96.4 % P2O5 acceptable: P2O5t., 77.39 and 79.54 % P2O5 w.s. : P2O5t., 6.03 and 7.08 % nitrogen, respectively. In the case of using HNO3, nitroammophosphate contains the largest amount of nitrogen due to additionally introduced nitric acid, but the phosphate raw material has a relatively low decomposition coefficient. The strength of granules of all brands of fertilizers averages 3.50 MPa and are quite suitable for bulk storage and transportation. Material balances for the production of ammophosphate, sulfoammophosphate and nitroammophosphate have been calculated.

Aerobic granulation in a continuous-flow simultaneous nitrification, endogenous denitrification, and phosphorus removal system fed with low-strength wastewater: Granulation mechanism and microbial succession

The culture of aerobic granular sludge (AGS) in continuous-flow system for treating low-strength municipal wastewater is still a challenge for its widespread application. This study developed a continuous-flow reactor based on metabolic and hydraulic selection pressure to explore the feasibility of culturing AGS in conventional continuous-flow mode. The results showed that aerobic granulation was successfully achieved with a mean particle size of 373 μm and almost all granules (95.6 %) were larger than 200 μm. An obvious three-stages granulation process comprised of initial adhesion, the formation of early aggregates that acted as nuclei of granules, and the final AGS maturation, was observed in this work. The selective enrichment of slow-growing bacteria in alternating feast/famine condition played a critical role in the aerobic granulation. The analysis results of extracellular polymeric substances revealed that β-polysaccharides and proteins distributed uniformly within the mature granules, while α-polysaccharides were found mainly concentrated around the granules, which was believed to enhance the mechanical strength of granules. The continuous-flow AGS system exhibited an excellent simultaneous carbon, nitrogen, and phosphorus removal performance with high removal efficiencies of NH4+-N (97.6 %), TIN (91.0 %), COD (93.7 %), and TP (94.8 %). Moreover, a low sludge yield of 0.1 gMLSS/gCOD was obtained for dramatic in situ sludge reduction. Illumina MiSeq sequencing results confirmed the outstanding accumulation of GAOs (Candidatus_Competibacter) and PAOs (Rhodocyclaceae) in the system, which were responsible for simultaneous C, N, P removal and sludge reduction. Overall, this study demonstrated the feasibility of aerobic granulation in conventional continuous-flow mode and offered insights into the granulation mechanism, providing implications and references for the application of AGS technology in existing wastewater treatment plants.

Development optimization and performance evaluation of mineral capsules based on magnesium oxide expansive agent

Mineral capsules could improve the self-healing ability of cement-based materials by avoiding the premature reaction of minerals. This study mainly optimized the preparation process of mineral capsules and comprehensively evaluated the influence of mineral capsules on the mechanical and self-healing properties of cement-based materials. By incorporating different contents of magnesium oxide expansive agent, the basic properties of mineral capsules were investigated and the optimal dosage of healing agent was determined. The encapsulation effects of polyvinyl alcohol and epoxy resin were compared to identify the better wall material. Then the mechanical and self-healing properties of the mortar mixed with different amounts of mineral capsules were comprehensively analyzed. Results from the healing potential, granule strength and soundness of mineral cores indicated that the optimal dosage of magnesium oxide expansive agent was 60 wt%. Compared with polyvinyl alcohol, mineral capsules encapsulated with epoxy resin had higher granule strength and better alkali resistance. Although the addition of mineral capsules had a negative impact on the compressive strength of mortar, the self-healing performance was significantly improved. With increasing contents of mineral capsules, the cracked mortar obtained more pronounced crack closure and impermeability recovery.

DEM simulation of a single screw granulator: The effect of liquid binder on granule properties

The Caleva UK single-screw Variable Density Extruder (VDE) is a continuous powder processing equipment known for spheronization and extrusion. Its suitability for granulation remains uncertain, a common challenge in powder processing industries that deal with granules, pellets, and tablets. This study investigates the VDE's potential for granulation, using 65 µm CaCO3 powder and PEG 4000 as a liquid binder. In order to replicate several experimental setups with varying binder concentrations and liquid-to-solid ratios (L/S) of 0.1 and 0.15, eight DEM simulations were run. Our results indicate that higher binder concentrations yield more consistent products with fewer fines, while lower concentrations result in inconsistent products with increased fines. Low L/S ratios produce fragile, fine-sized products with a broad particle size distribution (PSD). DEM simulations reveal a direct relationship between liquid binder content and contact forces. Analysis of bonds formed, and particle counts in simulations corroborates experimental observations of fines production. Additionally, granule strength appears to be directly proportional to contact force.

Obtaining ammophosphate and sulfoammophosphate fertilizers on base of the washed dry concentrate containing 26% P2O5

The process of obtaining ammophosphate by means of phosphoric acid decomposition of washed dried concentrate (WDC with 26% P2O5 and 10% CO2) - raw material for the production of thermally fired concentrate, has been studied. The wet process phosphoric acid (WPA) contains (wt.%): 16.46 P2O5, 0.06 CaO, 1.11 MgO, 0.27 Fe2O3, 0.41 Al2O3, 2.98 SO3 and 0.99 F. The weight ratio of WPA:WDC ranged from 100: 10 to 100: 30. Then acidic phosphate pulps (at 65 °C) after 45 minutes were ammoniated to pH = 3.8, granulated and dried at 85-90 °C. It has been shown that the nitrogen content in the finished product ranges from 4.92-7.11%, total phosphorus (P2O5t.) 41.48-46.44%, phosphorus acceptable by citric acid (P2O5ac.c.a.) 34.79-45.11%, phosphorus form of water soluble (P2O5w.s.) 23.49-37.73%. Weight fractions of H2SO4 - 5 and 7.5 were optimal and the product contains 37.6 and 34.47% of P2O5t.; 24.11 and 22.06% CaOt., 88.75 and 92.40% P2O5ac.c.a.by citric acid: P2O5t., 84.21 and 89.7% P2O5ac.tr.b. by trilon B: P2O5t., 77.39 and 79.54% P2O5w.s.:P2O5t., 6.03 and 7.08% nitrogen, respectively. The strength of granules of fertilizers averages 3.50 MPa and are quite suitable for bulk storage and transportation.

Granulation of nanocomposites based on glauconite and urea: binding materials and characterization of activated mineral fertilisers

Relevance. Development of controlled release fertilisers and their granulation is at the forefront of agriculture and environment. With growing world population and increasing food demand, agriculture faces the challenge of efficient resource management and increased crop yields. In this environmentally friendly and easy to obtain and use fertilisers become a key element for sustainable development of agribusinesses. Aim. To study the complete cycle of creation of granular fertilisers based on new materials, including aggregation of mineral particles with different binding solutions and mechanochemical activation of initial mixtures of glauconite and urea. Potassium-containing clay mineral – glauconite of Karinskiy deposit (Russia) was used as a "container" material. Urea containing up to 46 wt % of nitrogen was used as an additive (nutrient) component for fertilisers. The following parameters were stable during mechanochemical preparation: mineral/urea ratio and abrasion type. Solutions with different nitrogen concentrations were used as binders during granulation. The methodology for investigating the characteristics of the resulting nanocomposites included particle size analysis, X-ray diffraction analysis, scanning electron microscopy, and FTIR spectrometer. Results. The advantages of different granulation options for mechanochemically activated composites were investigated. The authors have produced f full cycle of controlled-release granular fertiliser. The average nitrogen content in glauconite particles reaches 5.5 wt %. The granule size depends on the content of urea gel concentrate in the binder. The maximum strength and proportionality of granules are achieved, when using a binder consisting of 100% urea gel concentrate. Determination of the optimal content of gel concentrate in the binder used in granulation plays a key role in obtaining strong fertiliser granules.

Strength Formation and Failure Mechanism Analysis of Cement-Stabilized Laterite Granules Based on Numerical Simulation

The poor grading and significant differences in the mechanical properties of laterite granules in West Africa limit the application of this typical material in road structures. In this paper, the poorly graded laterite granule was blended with fine sand and stabilized with cement to improve the strength of laterite granules. An innovative combination of laboratory tests and numerical simulation analysis using the numerical simulation software PFC2D 5.0 was used to investigate the cement-stabilized laterite granule’s strength formation and failure mechanisms. Laboratory test results show that when the sand content is 40%, the grading curve is close to the maximum theoretical density lines (MTDLs), and the unconfined compressive strength of cement-stabilized laterite granules increased by 35.2% as the cement dosage increased from 2.5% to 5.0%. Numerical simulation tests show that the strength failure of cement-stabilized laterite granules is shear. The failure surface is tilted and through with the axial direction, and the compressive and tensile stresses between the particles cause the failure of the specimen. The simulation test results are close to the laboratory test results, and the deviation rate is less than 10%. It can guide the optimal grading design and strength prediction of cement-stabilized laterite granular materials and provides a basis for reducing laboratory tests and accurate design for such research in the future.

Effect of Gangue Distribution on Compressive Strength of Iron Ore Granules

Effect of Gangue Distribution on Compressive Strength of Iron Ore Granules

Inorganic capsule based on expansive mineral for self-healing concrete

Expansive minerals are extensively used to promote the self-healing performance of the cracked concrete. Nonetheless, the expansive minerals will be consumed prematurely by participating in cement hydration. In this study, two types of inorganic capsules based on magnesium oxide expansive agent were developed by the techniques of granulation and encapsulation. The superabsorbent polymer was also embedded in inorganic capsules to enhance the healing ability. To investigate the healing potential and durability of the inorganic capsules in cement matrix, the mineralogy of inner core, granule strength and encapsulation effect were measured. The self-healing efficiency was evaluated by the tests of crack observation, water permeability and microstructure analysis. Results showed that the inner core of inorganic capsules remained stable during granulation, and the protective shell endowed the capsules with considerable strength and erosion resistance. Due to the addition of inorganic capsules, especially the capsules containing two-component healing agents, the effects of crack closure and impermeability recovery of the cracked mortar were significantly increased after healing in wet-dry cycles. The self-healing products consisting of calcite and Mg-rich phases were formed by the reaction of healing agents. The formation of the Mg-rich products was further accelerated owing to the continuous water supply by the superabsorbent polymer inside inorganic capsules.

Utilization of green liquor dreg in lightweight aggregates: Effect of texture on physical properties

Green liquor dreg (GLD) is a side stream generated by pulp industry. Due to its complex physicochemical nature, it has been reported to be difficult material to utilize. Here, a novel approach towards utilization of moist and dry green liquor dreg as binder and filler in alkali-activated lightweight artificial aggregates was developed. Dried GLD and moist GLD were granulated with blast furnace slag (BFS) and Bioash in different mixtures using alkali activation. The effect of the GLD nature (dried and moist) on strength, microstructure and durability of the lightweight granules were determined and compared. Results show that the method used in homogenizing the moist GLD and other powders was efficient and improved the frost resistance. The reaction product identified in the granule’s includes calcium silicate hydrate, Mg–Al layered double hydroxides, and ettringite. These results demonstrate the potential of GLD as a binder and fillers in cementitious applications.

Preferred Characteristics of Starch Powder for Producing Starch Pearls by Disc Granulation

AbstractNine representative starches (amylose content 1.9%–67.1%) from cereals, tubers, and legumes are selected as raw powders to produce starch pearls by disc granulation. All starch powders could be granulated into starch pearls, but the starch pearls made from waxy and high‐amylose corn starch are unable to withstand cooking. Cluster and Pearson correlation analysis further indicates that to produce starch pearls with high granule strength and good cooking and texture qualities, the selected starch preferably has the following characteristics: 1) a lower amylose content (ranging from 25.9%–41.6% in this study); 2) a lower pasting temperature; 3) a higher ratio of amylopectin extra‐long chains (DP ≥ 36) to amylopectin short chains (DP 6–12); 4) a larger particle size. Among the nine starches, potato and cassava starches are the most suitable for producing starch pearls by disc granulation. In addition, it is suggestive that Rapid Visco Analyzer analysis of starch powder can be used to rapidly predict the critical cooking and texture qualities of starch pearls, including transparency, hardness, and chewiness. This study not only provides an economical method to produce starch pearls, but also establishes a preliminary theory for selecting starch raw materials.

Technology for production of granular porous ammonium nitrate

The physicochemical principles of the process were considered and a new technology for the production of granular porous ammonium nitrate was developed that is suitable for integration into the existing production of complex mineral fertilizers. The methods for preparation of porous ammonium nitrate were proposed and the effect of various additives on the strength of granules was investigated. The dependence of the sorption capacity of brand B ammonium nitrate granules, which contains 0.3–1.0% H2O, on the number of heating and cooling cycles was been studied. It was established that when the granules are heated to 1300C and cooled to 300C, the required liquid fuel sorption capacity, equal to at least 10 g/100 g, can be achieved in two heating and cooling cycles. When heating the granules to 900C and cooling to 300C, five heating and cooling cycles are required to achieve the same value of sorption capacity. The technology and the proposed flow diagram of fabricating granular porous ammonium nitrate based on the existing equipment for the production of complex mineral fertilizers was developed. The parameters of the process of obtaining a product that meets the requirements of the technical conditions were optimized. It was shown that the production of porous ammonium nitrate is possible by mixing an 82–84% solution of ammonium nitrate with phosphogypsum followed by granulation and drying in a drum granulator-dryer, classification and heat treatment of granules with a size of 1–3 mm. To obtain strong granules, sulfate-phosphate additives are introduced into the ammonium nitrate solution, the source of which is phosphogypsum, a waste product from the production of orthophosphoric acid. The suggested use of a two-section mixer for carrying out the interaction of an ammonium nitrate solution with phosphogypsum ensures the minimum mixing time of the reagents.

Comparative analysis of granule properties in continuous granulators

An experimental study into twin screw granulation (TSG) has been performed using a design of experiments (DoE) approach. The properties of the produced granules are compared to those reported previously from a range of continuous and batch granulation processes. The effect of processing parameters such as speed, temperature and binder content on granule strength and structure are analysed. Seeded granule structures were found to be present in all but one type of granulator (Extrudomix) and longer residence times were found to lead to maximum seeded structures with a batch Cyclomix granulator. Granule crushing strengths were found to be higher in TSG than all other continuous equipment and the optimum condition for the formation of stronger granules with the lowest variation was around 65.4 °C. Overall, an equipment-specific DoE approach was shown to be a useful method to establish the relationship between process parameters, structure and properties.

Slow release fertilizers based on polyphosphate/montmorillonite nanocomposites for improving crop yield

Nanocomposites are promising materials for the development of novel and environmentally friendly fertilizers that can delay the release of nutrients. In this study, a novel high-strength spherical nanocomposite fertilizer was prepared via agglomeration and granulation using montmorillonite, urea phosphate, urea, and potassium chloride as raw materials. The properties and morphology of the prepared fertilizer were characterized by Fourier Transform Tnfrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Thermogravimetric Analysis (TGA) and X-ray Computed Tomography (XCT) techniques. FT-IR analysis identified the formation of polyphosphate in fertilizer and hydrogen bonds between polyphosphate and montmorillonite. XRD analysis showed increased montmorillonite interlayer spacing and confirmed the formation of polyphosphate-montmorillonite nanocomposites. The effects of raw material mass ratio, reaction time, and reaction temperature on the strength and fluidity of nanocomposite fertilizer granules and the optimum preparation process was obtained by the response surface method (RSM-CCD). The optimum preparation process was obtained as follows: reaction temperature, 103 °C; reaction time, 237 min; and mass ratio, 1:1:0.93:1 (urea phosphate: urea: potassium chloride: montmorillonite). Under these optimum conditions, the particle hardness and angle of repose of the prepared fertilizer were 64.75 ± 0.48 N and 30.84 ± 0.95°. Nutrient release and agronomic effectiveness of the fertilizer was evaluated using column leaching and pot experiments, respectively. The column leaching experiment and XCT analysis demonstrated that the nanocomposite structure was responsible for the slow nutrient release. The pot experiment showed that compared with the traditional fertilizer, the soil nitrate and available phosphorus was increased by 28.02% and 43.45%, respectively, and the maize yield was increased by 24.27% with the application of prepared fertilizer. This work provides support for the preparation of high-strength spherical nanocomposite fertilizers and their large-scale applications in modern mechanical agriculture.

Influence of the amount and fineness of grinding of ammonium sulfate on the properties of sulfate-containing urea

The objective of this work is to determine the optimal technological mode for obtaining sulfated urea with a balanced content of nitrogen and sulfur by adding ammonium sulfate to the urea melt before granulation. The article presents the results of a study of the dependence of the properties of sulfated urea on the degree of grinding and on the amount of ammonium sulfate, expressed by the mass ratio of CO (NH2)2: (NH4)2SO4 = 100 : (2.5-50). Methods for obtaining, granulating and studying the properties of sulfated urea samples are presented. In fertilizers obtained with the addition of ammonium sulfate to the urea melt at the studied ratios, the strength of the granules increases from the initial 2,53 to 4,80 MPa, the gyroscopic point decreases from 58,4% to 52,3. It was also revealed that when ammonium sulfate is added to the urea melt, the density and viscosity of the melt increase with an increase in the amount of ammonium sulfate introduced. At 135 ° C, an increase in the addition of ammonium sulfate from 2,5 to 50,0 mass parts per 100 mass parts of urea leads to an increase in density from 1,162 to 1,412 g/cm3, viscosity from 2,56 to 7,91 cΠɜ. It was found that the smaller the particle size of ammonium sulfate, the higher the strength of the urea granules. With a decrease in the dispersion of ammonium sulfate particles from 0,25 to 0,04 mm, the strength of sulfated urea granules increases, the presence of ammonium sulfate in the composition of urea reduces the dissolution rate, which makes it possible to prolong their action, in addition, it lowers the pH of the product, which prevents the release of ammonia during storage and transportation sulfated urea.

Effects of the size polydispersity and friction coefficient on the compressive strength of wet granular materials

We numerically study the effects of the size polydispersity and the friction coefficient on the compressive strength of wet granules under a diametrical compression test by using discrete element simulations. The nu-merical method is coupled with the capillary cohesion law which is enhanced by the cohesive forces between grains in the pendular regime. The wet granules are composed of primary spherical particles whose size poly-dispersity is varied from1 to 10 and the friction coefficient between grains is varied from0.1 to 1.0. By applying a constant compression velocity on the top plate in quasi-static regime, the granule is deformed but does not abruptly rupture due to the cohesive effects between grains and the rearrangement of primary particles. This no abrupt rupture is characterized by the appearance of the peak compressive stress in a long vertical strain before the onset failure of the granule. The compressive strength of the granule increases with increasing the friction coefficient for all cases of the size polydispersity but seemly declines for low values of the size polydispersity and almost level-off for high-size polydispersity with the friction coefficient larger than 0.5.